Method of producing a pile fabric



Feb. 20, 1968 o JR 3,369,948

METHOD. OF PRODUCING A FILE FABRIC Filed NOV. l2, 1964 INVENTOR BERNARD GEORGE OSTMANN, JR.

BY @M @9414 ATTORNEY United States Patent 3,369,948 METHOD OF PRODUCING A PILE FABRIC Bernard George Ostmann, Jr., Wilmington, Del., assiguor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Nov. 12, 1964, Ser. No. 410,484 1 Claim. (Cl. 156-72) This invention relates to the provision of improved textile materials, and more particularly to pile fabrics which have a combination of softness, lightfastness, and drycleanability.

In US. Patent 3,085,922 to Koller there are described porous, bonded, self-supporting fibrous sheets which are useful for laminating to various backing materials to produce pile fabrics for use in apparel and industrial textile applications. The present invention relates to pile fabrics of that general type but of special construction so as to exhibit an exceptional combination of dry-cleanability, lightfastness and a very soft hand. This combination of.

properties renders the pile fabrics especially useful as blankets, outerwear, and innerlinings having a new feeling of softness.

In accordance with the invention there is provided a textile article comprising a backing adhered to a face of at least one porous, flexible, self-supporting layer composed of substantially parlallelized crimped fibers attached to one another at a plurality of contact points throughout the three dimensions of the layer by a binder, said layer having faces composed essentially of fiber ends; the improvement wherein said fibers and said binder are each linear polyesters having recurring intralinear linkages as an integral part of the polymer chain, the polyester binder being normally solid and having a melting point below that of said polyester fibers, the major portion of said polyester binder being in the form of small rounded fused particles at isolated points along the polyester fibers, and the particles binding an average of no more than 2.5 fibers per particle and being of such size that the average largest dimension thereof is not more than about 0.009 inch and the average minor dimension thereof is not more than 0.005 inch.

The improved textile articles of the invention are formed by providing an assembly of substantially parallelized crimped polyester fibers. Within the assembly polyester binder is first uniformly provided throughout with substantially no fiber-to-fiber bonds and the assembly is then heated at a temperature between the melting point of the polyester binder and the polyester fiber to thereby cause the polyester binder to retract into droplet form and thus bond polyester fibers to one another at their cross-over points. The bonds obtained by this technique are of relatively small size, on an average bond but a few fibers together, and are of a very efficient geometrical shape, e.g. normally being generally spherical or ellipsoidal.

To illustrate the foregoing, a typically suitable method for preparing the improved bonded textiles of this invention will now be given. Polyethylene terephthalate staple fibers were carded into a web which was sprayed with a 4% by weight solution in methylene chloride of a copolymer of ethylene terephthalate with ethylene isophthalate (79/21 molar ratio), then the sprayed web was dried and recarded, then formed into a sliver. The recarding operation effectively broke up the bulk of any fiberto-fiber bonds since the best properties are achieved when these are created in the subsequent fusion stage. Other chlorinated hydrocarbon solvents, such as 1,1,2-trichloroethane may be used to dissolve the copolyester binders and other concentrations (e.g. 1-15% by weight) of the binder in the solvent have been found suitable. The sliver was cut into sections to fit the depth of a steel mold and aligned in the mold in a vertical direction, with the ends of the slivers in the top and bottom faces of the mold. The assembly of essentially unbonded aligned fibers with the polyester binder distributed uniformly throughout was placed in an air oven and heated to 220 C. (428 F.) for one hour in order to fuse the binder composition and attach the fibers together. The bonded fiber block so obtained was removed from the mold after cooling and thin (0.25 inch thick) sheets were sliced by a band knife in such a way that the cutting blade was perpendicular to the direction of the fiber alignment. The sheets were each sprayed with 1.0 ounce per square yard (34 g./sq. meter) of an adhesive composition which consisted of an 11% by weight solution in methylene chloride of a copolyester resin consisting of repeating ethylene terephthalate and ethylene azelate units (60/40 molar ratio). A layer of woven cotton scrim fabric was pressed lightly against each of the coated thin bonded sheets and the assembly held together in an oven at 177 C. for 5 minutes to produce an improved laminated fabric of this invention.

Although the amount of binder composition used in the porous fiber assembly is not as critical as the morphology and distribution of the binder particles, there will normally be used between 5% and 50% binder by weight of the structural fibers in the porous fiber assembly layer, and preferably 7-12% The preferred thermoplastic binder compositions are copolyesters of ethylene glycol with a dibasic acid component comprising a major proportion of terephthalic acid with a minor proportion of one or more other acids such as isophthalic acid, hexahydroterepht-halic acids, and saturated aliphatic dicarboxylic acids having C C carbon atoms per molecule. The copolyesters may be prepared from two or more acids or their ester-forming derivatives.

Linear homopolyesters and copolyesters of a variety of other combinations of polyhydroxy compounds, e.g. diethylene glycol, hexamethylene glycol, and the above or other dibasic acids can also be used. Similarly hydroxy acids and lactones can be formed into suitable polyesters as is known in the art.

A major consideration in the selection of a polyester binder is that it be a normally solid polymer and have a melting temperature below the melting point of the polyester fibers. The melting point should preferably be above temperatures experienced in dry-cleaning and washing of fabrics, e.g. above at least 120 F. The polyester binder should be film-forming, i.e. have a molecular weight of 5000 or more. Advantageously the polyester binder will be insoluble in commercial dry-cleaning solvents such as perchlorethylene. The relative viscosity, of the binder should be at least 20, and will preferably be within the range of 2045. The relative viscosity referred to is based on viscosity measurements of the copolyester binder dissolved at a concentration of 8.8% by weight in a solvent mixture of phenol and 2,4,6-trichlorophenol (59% /41% by weight), measured at 25 C. (77 F.). Typically suitable binders arecopolyesters of ethylene glycol with a mixture of acids such as terephthalic/isophthalic acid in the ,molar ratio of 2580/ 20, terephthalic/azelaic or other C C acids in the molar ratio of 60/4075/25, etc.

Typical polyester structural fibers for achieving the combination of improved properties in the textile laminates are linear polyesters and copolyesters, such as polyethylene terephthalate, condensation products of ethylene glycol with a 98/2 mixture of terephthalic/S-(sodium sulfo)- isophthalic acids, trans-p-hexahydroxylylene glycol with terephthalic acid, sulfonate salt-modified polyesters, such as described in Grifiing et al. U.S. 3,018,272, self-elongating ethylene terephthalate polymers, and the like. Normally the structural fiber will have a denier of less than d.p.f., and preferably less than 6 d.p.f., the lower the denier in general, the softer the product. For some purposes it may be desirable to use blends of mixed deniers, mixed fiber lengths and/or mixed cross-sections. The fiber length, whether staple fibers or continuous filaments which have been cut, will generally be in the range of 1 inch (25.4 mm.) to 6 inches (152 mm.). It is also possible to modify the cross-section of the structural fiber or use blends of two or more fibers each having different cross-sections, including round, trilobal, ribbon, tetralobal, and other configurations. The crimp used in the structural fibers may be either essentially planar such as a zig-zag or stuifer-box crimp, or a three-dimension crimp may be used such as the helical crimp described by Kilian in U.S. Patent 3,050,821,

Equally important to the critical selection of polyester binder and polyester fibers is the manner in which the binder is dispersed throughout the block of fibers. Thus, as disclosed in the aforementioned Koller patent, it is essential that the fibers be substantially parallelized, crimped, and attached to one another at a plurality of contact points throughout the three dimensions of the block. In accordance with the present invention, the polyester binder is first uniformly provided throughout an assembly of polyester fibers with substantially no fiberto-fiber bonds and the assembly is then heated to cause the binder to retract into droplet form and thus bond polyester fibers to one another at their cross-over points.

The uniform dispersion of polyester binder throughout the initially formed fibrous assembly may be accomplished in a variety of ways. In each of these ways, however, it must be uniformly distributed, preferably as fibers or other discrete particulate material. Individual particles may or may not be adhered to structural fibers. However, if the particles are actually adhered to the fibers, then on the average they should bond together very few fibers, i.e., such that in the assembly the average number of fibers associated with each binder particle is less than about 1.5, preferably less than 1.1.

One suitable method for uniformly providing binder particles throughout an initial fibrous assembly is to spray either a fine mist of an organic solvent solution of the binder or simply a melt of the binder uniformly upon a carded web of the polyester fibers. The sprayed Web may be then recarded to remove the bulk of any fiberto-fiber bonds, i.e., so that each polyester binder particle will, for the most part, be attached to a single fiber. Of course, if the web is widely spread to a very low density before spraying, few fiber-to-fiber bonds will be created and the recarding step can be avoided.

Another suitable method for providing binder in particulate form throughout the initial fibrous assembly is to impregnate an assembly of unbonded fibers with an aqueous dispersion of the polyester binder followed by removal of excess impregnant and evaporation of Water to leave a particulate residue. Still a third suitable method is to shake powdered particles of polyester binder throughout the interstices of the fiber assembly. A fourth method involves blending with the structural polyester fibers a polyester binder in the form of a second fiber component and then carding the blend of fibers to insure the uniformity of the mixture. The preferred binder content for this latter method is l5%25% based on the weight of the structural fiber.

Regardless of the manner in which the assembly of polyester fibers and binder is formed, a subsequent step is then performed in which the assembly is heated to a temperature above the melting point of the polyester binder but below the melting point of the structural polyester fibers. As a result of the heating, the dispersed polyester binder is caused to flow and retract into the form of small rounded, droplet-like fused particles and in this fashion bond the structural fibers to one another at their cross-over points.

The exact nature of the polyester binder particles in the final product Will be particularly evident from a consideration of FIGURES 1 and 2. These drawings illustrate the appearance of a product of the prior art and one of the invention when examined microscopically. In FIGURE 1, representing a prior art productspecifically one produced by the method of Example I given hereinafter, the polyester binder is dispersed in the form of large agglomerates which surround large sections of the fibers and associate large numbers of fibers with each binder agglomerate. In constrast, a product according to the invention, specifically that of Example II, is shown in FIGURE 2 to have binder particles in the form of generally spherical and ellipsoidal shaped droplets. While many of these droplets unite two, three, or even more fibers at their cross-over points, others are attached to a single fiber.

Sufiicient binder is used to attach many fibers at their cross-over points, but sometimes there is additional binder which is in the form of small rounded particles attached at isolated points along some of the fibers between their cross-over points. It is important in order to obtain the high degree of softness in the final textile, that the binder does not coat the fibers continuously but leaves the fibers flexible enough to bend except by the amount of resistance offered by the bond points at the fiber cross-overs.

A critical measure of the proper distribution of the binder in the porous fibrous layer is that on the average binder particles bond, i.e., are associated with, not more than 2.5 fibers per binder particle. This discovery is important to the production of good aesthetics in the final products of this invention. For purposes of determining the average number of fibers reported per binder particle herein, representative sections of the bonded fiber layer are selected from the final textile product and using a microscope the total number of binder particles is counted in the representative section, along with the number of fibers associated with each binder particle. Then the total number of fibers associated is divided by the total number of binder particles counted to give an average number of fibers per binder particle in the representative section selected for measurement.

It has also been found that if the morphology of the binder particles is such that they are so large as to form agglomerates and thereby cause more than an average of 2.5 fibers to become bonded together per binder particle, the softness and desirable aesthetics of the porous, bonded fiber layer is lost. An example of the latter situation of forming large binder agglomerates in which the average of fibers per binder particle is frequently greater than 25 occurs when the fiber assembly is dipped and completely immersed in a solution of the binder and then withdrawn and excess binder allowed to drain out of the fiber assembly. It has been found that the improved products of this invention should have porous, bonded fiber layers in which the binder particles have an average length of less than about 0.009 inch (0.23 mm.) and an average width of less than about 0.005 inch (0.13 mm), in order to insure that the products will have binder particles sufficiently small to provide satisfactory aesthetics.

In making the final textiles of this invention, any suitable backing material may be used such as thin layers of light-weight woven, knitted and non-woven fabrics, films, foam, foils and the like. The adhesive composition which is used to attach the porous, bonded fiber assembly to the backing may be composed of a variety of different polymer compositions which may easily be distributed uniformly on one or both faces of the two layers to be laminated without penetrating either layer very much. The adhesive may be applied by spraying or other means, preferably so as to leave approximately one ounce of adhesive dry WAFER AND LAMINATE TESTS The flexural rigidity or stiffness of the thin, porous, bonded fiber layers or wafers as measured herein was determined by following ASTM method D-1388-55T, and the stiffness reported in gram-centimeters. Another mea sure of softness in addition to the fiexural rigidity is the force required to compress the porous, bonded fiber Wafer to one-half its original thickness. This measure of softness is reported herein as compression of the wafer in pounds per square inch grams/ sq. cm.). The lightfastness of the wafers reported herein was determined by exposing the wafers for stated periods of time in a Fade-Ometer according to the conditions specified in AATCC Standard Test Method 16A-1957. The resistance of the laminated products of this invention to dry cleaning was tested and reported herein as a distortion rating. For this test, the laminate sample was subjected to a standard commercial dry-cleaning cycle by combining with the sample suflicient other garments to total a thirty pound (13.5 kg.) load for cleaning. This load was placed in a commercial Detrex dry-cleaning machine model No. 526 and agitated for 14 minutes at 7075 Fv (21.1-23.9 C.) with about 85 gallons (302 liters) of tetrachloroethylene containing 1.5-2% by volume of soap. The liquid was drained in one minute and the excess liquid removed from the garments as completely as possible by spinning for three minutes. The contents of the cleaning machine were transferred to a commercial Detrex tumble dryer for 15 minutes at 110120 F. (43.3-48.9 C.), after which the dryer was vented with fresh cool air for three minutes. After dry cleaning, the test laminate was examined for distortion of the pile layer, which refers to the degree of clustering of the fibers at the surface of the pile layer, in the laminate. The distortion rating after dry cleaning was derived by assigning arbitrary visual ratings on a scale of 1 to 5, where the highest rating of 5 indicated little or no distortion or clustering of the pile fibers, and 1 indicated extensive distortion or clustering. The distortion ratings reported herein were those measured on the laminates after each laminate had been subjected to five dry-cleaning cycles described above.

An advantage of the present invention is that it provides a unique combination of binder composition, morphology and distribution throughout a porous low density fiber layer so as to place the binder particles in a certain fashion to permit the manufacture of textiles having a very soft hand or aesthetics, satisfactory lightfastness and satisfactory washability and dry-cleanability. The preferred fiber density of the porous, bonded fiber layer is less than 3 pounds per cubic foot (48 g./ liter), and preferably less than 1 pound per cubic foot (16 g./liter), in order to achieve the highest degree of softness in the fabric. The present invention provides pile fabrics having a highly luxurious hand and other improved properties over similar pile fabrics made heretofore wherein a different combination of binder composition and distribution was employed.

The improved textiles of this invention may be prepared by varying the fiber and binder, backing and other variables as indicated to produce a variety of useful products such as those useful for blankets, bedspreads, dresses, outerwear jackets, innerlinings for coats, suits, ski jackets and pants, childrens wear, rainwear, snow suits, beach garments, upholstery liners, bathrobes, bath mats, and the like.

The expression polymer melting point employed in connection with the products of this invention is the minimum temperature at which a sample of the polymer leaves a wet molten trail as it is stroked with moderate pressure across a smooth surface of a heated metal. Polymer melting point has sometimes in the past been referred to as polymer stick temperature.

The following examples illustrate specific embodiments without intending to limit the scope of the claim. Examples II, V, VI, and VIII to X illustrate the practice of the invention whereas the others illustrate prior art techniques.

Example I This example illustrates the incorporation of binder according to prior art techniques.

A blend of staple fibers of ethylene terephthalate polymer having a three-dimensional helical crimp, 4 denier per filament and a staple length of 2 inches (5.08 cm.) were carded into a web with staple fibers of ethylene terephthalate polymer having a stuffer-box type of crimp, 1.5 denier per filament and a staple length of 1.5 inches (3.8 cm.). The final ratio of the staple fibers in the blend'was 60/40 parts, respectively, by weight.

The carded web was continuously wound onto a 2 foot (61 cm.) diameter circular drum with a minimum of tension until a layer approximately ten inches (25.4 cm.) thick was obtained. This layer of fibers was cut in a line transverse to the direction of the fibers and removed from the drum to give a batt of carded fibers measuring approximately 27 inches (68.6 cm.) wide by 75 inches (1.9 meters) long by 10 inches (25.4 cm.) thick, having the fibers all aligned in the same general direction along the length of the batt. The batt was cut at transverse to the direction of the fibers into sections 5 inches (12.7 cm.) long and 10 inches (25.4 cm.) thick. Each section was further cut generally parallel to the direction of the fibers to form segments 8.75 inches (22.2 cm.) in width. These segments were then carefully placed by hand into a perforated metal mold 8.75 inches (22.2 cm.) wide by 8.75 inches (22.2 cm.) long by 5 inches (12.7 cm.) tall, having an open top, with the 8.75 inch (22.2 cm.) sides of the segments face-to-face so that the fibers were all aligned in the same general direction with the fiber ends directed towards the open top and bottom of the mold. A total of 90-grams of fiber was packed into the mold. The mold was closed and slowly immersed in a binder solution of 580 grams of ethylene terephthalate/ethylene isophthalate (79/21 molar ratio) copolyester (1;, =29) dissolved in 11,700 cc. of 1,1,2-trichloroethane. After a residence time of four to six minutes, the mold was slowly withdrawn from the bath, allowed to drain free of excess binder solution and placed in an oven at 220 C. (428 F.) for one hour to remove the solvent and melt the copolyester binder. On removal from the mold, the fibers, now held together by the binder, were found to have a weight increase of 16.7% on the weight of fiber, representing the amount of binder present. The fiber density of the block was 0.9 lb./ft. (14.4 g./l.). The bound block was cut into thin wafers with a band knife slitter. Laminates were prepared from .156 inch (.4 cm.) thick wafers by spraying one side with an 11% by weight solution of ethylene terephthalate/ethylene azelate (60/40 molar ratio) copolyester in methylene chloride to give a final loading of 1.0 oz./yd. (33.9 g./m. adhesive (dry weight) on the wafer. The sprayed wafer was then brought into contact with a loosely woven cotton cloth in a heated zone and firmly pressed together by means of a pair of nip rolls, then allowed to cool. The laminates so prepared exhibited little or no distortion before dry cleaning, but had a harsh, stiff hand. After dry cleaning the laminates still had a stiff hand and, in addition, showed extensive distortion at the surface of the pile layer. No discoloration was noted in the wafer samples when exposed for 20 hours and 40 hours in the Fade-Ometer test. The flexural rigidity of a 0.25 inch (.635 cm.) thick wafer is indicated in Table 1 together with the compression properties and the quantitative distortion ratings before and after dry cleaning. It was concluded that these laminate samples were comparatively poor in both softness and resistance to dry cleaning. Examination of the structure under the microscope revealed that the major portion of the binder was in the form of masses of webbed or filmed binder encompassing a multiplicity of fibers and extending for considerable distances throughout the structure as essentially continuous ribbons. Because of this continuous nature, no exact dimensions of width or length could be assigned the masses. However, measurements were made of the major areas located between neckeddown portions of the complete binder masses and an average length of 0.034 inch (0.865 mm.) and an average width of 0.0076 inch (0.175 mm.) were assigned. The number of fibers encompassed or held by these major areas were counted and found to average 8 fibers per binder mass.

Example II This example demonstrates the practice of the present invention.

Several ends of carded sliver (approximately 200 grains) of the blend of two polyester fibers described in Example I were spread out to a width of inches (25.4 cm.), laid together in a parallel direction and sprayed With a methylene chloride solution of 2.5 weight percent of the copolyester binder =29) used in Example I. The solution was deposited as uniformly as possible on the sliver in the form of a fine mist from a De Vilbiss spray gun (model GA517704FF). The sprayed sliver was then recarded to obtain uniform distribution of the binder and to remove the bulk of any fiber-to-fiber bonds. It was then collected as a batt as described in Example I. The fiber, which at this point contained by weight of binder, was packed into a large (40 inches x 48 inches x 10 inches) (101.6 cm. x 122.0 cm. x 25.4 cm.) perforated mold to a fiber density of 0.9 lb./ft. (7.1 kg'./cubic meter) and heated at 220 C. (428 F.) for one hour. The bound block was processed into wafers and laminates and evaluated as described in Example I. Examination of the structure of the wafer layer under the microscope revealed that the majority of the binder particles were in the form of small ellipsoids or spheres having an average major dimension of 0.0077 inch (0.02 cm.) and an average minor dimension of 0.004 inch (0.01 cm.). The particles were located at random along the fiber lengths, forming bonds at such points as where two or more fibers cross. The average number of fibers per particle, however, was determined to be 1.9. No discoloration was noted in wafer samples exposed for and hours in the Fade-Ometer. In contrast to the wafer and laminate prepared in accordance with Example I, the products of Example II had a very soft hand and high resistance to dry cleaning as evidenced by very little distortion in the dry cleaning test. The laminate made in accordance with this example is useful for making a womans bathrobe.

Example III This example illustrates a prior art method for incorporating binder.

A mold containing the same amount and blend of fibers as described in Example I was dipped in a freshly prepared solution of 321 grams of the viscous urethane prepolymer product of a 1.6:1.0 molar ratio of 2,4- toluene diisocyanate and polytetramethylene ether glycol (M.W.=1,000), and 99 grams of castor oil in 13.25 liters of tetrachloroethylene. To this solution was added, just prior to block dipping, a solution of 3.3 grams of 4,4- methylene-bis-(2-chloroaniline) dissolved in 48 ml. of methylene chloride. After being drained of excess solution, the mold was placed in an oven at 149 C. (300 F.) for 2 hours to remove solvent and effect curing of the urethane resin. The cured block, which had a weight increase of 8% due to binder, was sliced into 0.25 inch (6.35 mm.) thick wafers and laminated in the same manner as described in Example I. The wafer prepared in this example developed a yellow coloration within 20 hours in the Fade-Ometer test, making laminates prepared with these wafers unsatisfactory for certain textile uses. In addition, the data in Table 1 indicates the laminates showed high distortion upon being subjected to the dry cleaning test.

Example IV This example also illustrates a prior art procedure.

A block was prepared in the same manner as described in Example III except that the concentration of solids in the dip bath was increased. The composition of this present bath was 617 grams of the urethane prepolymer, grams of castor oil, and 5.9 grams of the 4,4-methylenebis-(2-chloroaniline) dissolved in 13.25 liters of tetrachloroethylene. A weight increase of 11% was observed. Laminates prepared from 0.25 inch (6.35 mm.) slices cut from this block showed poor resistance to dry cleaning as shown in Table 1. On exposing the wafer for 20 hours in the Fade-Ometer a yellow coloration developed. Examination of the structure under the microscope revealed that the major portion of the binder was present as film-like or web-like particles but not of the same large size or continuous nature as those of the polyester binder masses formed in Example I. These present binder particles had an average length of 0.0143 inch (0.36 mm.) and an average width of 0.0063 inch (0.160 mm.) and the particles bonded an average of 3.6 fibers/particle.

Example V This example illustrates the practice of the invention.

Carded sliver of the blend of crimped polyester fibers described in Example I was sprayed with a 5% solution of polyethylene terephthalate/ethylene azelate (60/40 molar ratio) in 1,1,2-trichloroethane using a De Vilbiss (model IGA502) hand spray gun equipped with an PX tip and a 704 air cap. A delivery pressure of 5 p.s.i. (351 g./cm. and an atomizing pressure of 70 p.s.i. (4.9 kg./ cm?) were employed. At this point the major portion of the binder (11% on weight of fiber) is present either as thin discontinuous sheaths around the fiber or as minute droplets. The dried sliver was recarded to break up fiberto-fiber bonds and formed into a batt on a garnett machine. The batt was cut into sections of a size appropriate to fit into the mold described in Example I and packed to a fiber density of 0.9 lb./ft. (7.1 kg./cubic meter), and heated for one hour at 190 C. (374 F.). The block was then sliced into 0.25 inch (6.35 mm.) thick wafers, laminated, and evaluated as described in Example I. Examination of the structure under the microscope revealed the majority of the binder particles to be small ellipsoids and spheres of the order of 0.0015-0.0020 inch (.038- .051 mm.) in the smallest, dimension. The resulting laminates after being subjected to the dry cleaning test did not show any severe distortion of the pile surface and hence were useful for a variety of apparel fabrics.

Example VI This example further illustrates the practice of the invention.

Carded sliver was sprayed with the same copolyester binder as in Example V except that a 10% solids solution was applied using a delivery pressure of 10 p.s.i. (700 g./cm. and an atomizing pressure of 20 p.s.i. (1.4 kg./ cm. Under these conditions the major portion of the binder was deposited on the fiber in the form of large droplets with some webbing. A weight increase of 15% was obtained. After processing, curing and slicing as in Example V, the binder particles in the final structure were found to be mainly large spheres and ellipsoids of the order of 0.0030. 00-8 inch (.076203 mm.) in the smallest dimension. The resulting laminates had a combination of satisfactory dry cleaning resistance, aesthetics and lightfastness for a variety of apparel fabric uses.

Example VII This example also illustrates a prior art method for incorporating binder.

A block was prepared from the same fiber and blend and in the manner as described in Example I using a dip solution composed of 600 grams ethylene terephthalate/ ethylene azelate (60/40 mole ratio) copolyester dissolved in 12 liters of 1,1,2-trichloroethane. After being drained of excess solution, the mold and contents were placed in A gave a soft laminate. After being dry cleaned five times in a commercial dry cleaning system, the laminate had a pleasing appearance.

Microscopic examinations of both wafers showed that the binder was distributed in small discrete dnoplets along an oven and heated at 190 C. (374 F.) for one hour. 1 the fibers with an average of two fibers per bonding par- The block, which showed a weight increase of 7.8%, was ticle. Analysis of the batt by extraction with methylene sliced into 0.25 inch (6.35 mm.) thick wafers which were chloride indicated the presence of 15% soluble material. processed and evaluated in the manner described previ- Example IX ously in Example I. The laminates and waters had the properties indicated in Table 1, which shows they had Thls xample according to the invention ses dry parpoor resistance to dry cleaning and poorer aesthetics ho of blnder. compared with the laminates made with the same retained A 60l00 mesh powder of a copolyester made from amount of binder applied by spraying. ethylene glycol and a 60/40 molar ratio of terephthalic TABLE 1 Softness of 0.25 inch Laminate Distortion Percent (6.35 mm.) Wafer 2 Rating 3 Example Binder Composition Binder on Method of Binder Weight of Application 7 Compression, Flexural Total Wafer p.s.i. Rigidity; Before After g.-cm.

5.3 1.9 4.7 2.7 5 .3 .5 4.0 14.3 2.9 9.0 2.7 1.1 1.7 4.2 7.1 Dip 1.9 2.6 2.5 5. 2 (Fine) Spray. .82 .8 3.0 4. 8 (Coarse) Spray. 29 1 3.0 10 (Fine) Spray 1.3 2. 2 3. 5 10 (Coarse) Spray .4 .8 3. 0 12.7 Di 1.9 5.5 3.5 13.5 (Fine) Spray- 1.4 2.3 3.5 13.1 (Coarse) Spray.-- .8 .5 3.5 6.9 Dip .65 .71 2.0 10 Dip .91 .96 2.5

l The data in Table 1 for the unnumbered examples was collected from experiments carried out following the same general procedure, with the difiereiices as listed, as that used in the corresponding numbered examp es.

Example VIII This example relates to the use of an aqueous dispersion of binder in accordance with the invention.

A. In a polyethylene bag was placed 135 grams of the =60/ blend of the fibers described in Example I and 200 grams of aqueous dispersion containing 28 grams of a copolyester prepared from ethylene glycol and a 60/40 molar ratio of terephthalic acid and azelaic acid. The fiber was impregnated with the dispersion so that no separate liquid phase was present and then spread to dry in air. The dried mixture was g-arnetted twice to form 9" wide batts. One hundred and six grams of this batt was cut into 5" segments that were packed into a metal cage measuring 9" x 9" x 5 with the fiber direction parallel to the 5" dimension. The packed block was heated for one hour in an oven at 180 C., removed from the cage and sliced perpendicular to the fiber direction into wafer A" thick. A polyester adhesive as used in Example I was applied to one face of the wafer by solution spraying and the wafer was subsequently thermally laminated to a cotton fabric. The laminate had a soft pleasing hand and even after being submitted to five commercial dry cleaning cycles, the laminate had a pleasing appearance.

1B. The same polyester dispersion used in A was applied to 135 grams of a web of the fiber blend of Example I by spraying to give a weight gain of 24 grams after air drying. The sprayed web was garnetted twice to fonm a 9" wide batt. One hundred and six grams of the batt was cut into the 5" segments and packed in a 9" x 9" x 5" metal cage so that the fibers were parallel to the 5" dimension and heated in an oven for one hour at 180 C.

The metal cage was dis-assembled and a bonded block of substantially parallelized crimped fibers having a fiber density of 0.9 lb./cu. ft. was removed. The block was sliced perpendicular to the direction of the fibers to give sheets thick. The sheets were light straw colored and of good strength. Lamination of the wafer to a cotton fabric with a thermoplastic copolyester adhesive as in 2 The higher values for both compression and flexural rigidity indicate harder products, whereas the lower values indicate softer products.

3 The distortion ratings for some of the laminates in Table 1 are reported both before the dry cleaning test, as well as after the test.

acid and azelaic acid was applied to slivers of the 60/40 blend of the fibers of Example I by shaking 5 grams of powder with 17 grams of sliver in a polyethylene bag. The sliver was turned and opened during the shaking to etfect even distribution. This procedure was repeated six times. Each batch was placed in the oven at 195 C. for a few minutes to melt the adhesive. The lot was then combined into 9" wide batts by garnetting twice to uniformly disperse the binder and break up fiber-to-fiber bonds. One hundred and ten grams of this batt was cut into 5 segments and packed in a 9" x 9 x 5" metal cage with the fibers substantially aligned and parallel to the 5" direction and the block was then heated at C. for one hour. The cage was disassembled and the block was removed and cut in the direction perpendicular to the direction of fiber alignment to give A" wafers. The waters were white and quite soft. Microscopic examination of the wafer showed that the binder was distributed as droplets at cross-over points. Extraction of the wafer with methylene chloride to remove the binder gave a weight loss of 12.5%. The wafer was laminated to a cotton fabric with a thermoplastic polyester adhesive. After being dry cleaned in a commercial system five times, the wafer was soft and undistorted.

Example X sure uniform dispersion throughout. The sliver so formed was then packed into a rectangular mold with the fibers all generally aligned in the same direction to give an assembly having a total fiber density of 1.5 1b./ft. The assembly was then heated in an oven at 400 F. to melt the low melting binder fibers and thus provide a bonded block having a binder content of about 43% based on the fibers. Wafers of different thicknesses were cut from the block and laminated to a woven cotton backing using the adhesive as described in Example I. The fabrics had a very soft hand and exhibited low distortion even after dry cleaning cycles.

B. Part A was repeated except that the molar ratio of terep hthalic acid/isophthalic acid in the binder polyester was 79/21 and the weight ratio of structural fibers to binder fibers was 80/20. The heating at 400 F. was conducted for 20 minutes giving a block having a fiber density of 0.9 lb./ft. Fabrics formed from wafers cut from the block were very soft and highly resistant to distortion. Other fabric properties were as follows:

Softness of 0.25 inch (6.35 mm.) wafer:

Compression, p.s.i .6

Flexural rigidity, g.-cm. .2 Laminate distortion rating:

Before 4.3

After 4.1

As many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not to be limited to the specific embodiments thereof except as defined in the appended claim.

What is claimed is:

1. A method for producing a textile article which comprises:

blending 5095% by weight structural fibers with 5 50% by weight binder fibers, both structural and binder fibtrs being crimped staple-length fibers composed Of linear polyesters, the polyester making up the binder fibers being normally solid and having a melting point below that of the polyester making up the structural fibers;

carding the blend of fibers to substantially parallelize the fibers and ensure uniform dispersion of the binder fibers and structural fibers;

stacking the carded blend to form a multi-ply assembly with the fibers all generally aligned in the same direction;

heating the assembly at a temperature between the melting point of the binder fibers and the melting point of the structural fibers to thereby cause the polyester making up the binder fibers to retract into droplet form and bond the structural fibers to one another at their cross-over points throughout the assembly;

cutting the assembly at an angle transverse to the parallelized fibers to provide a porous, flexible, self-supporting sheet having faces composed essentially of fiber ends; and

laminating a face of the sheet with a backing.

References Cited UNITED STATES PATENTS 2,604,427 7/1952 Armstrong et al. 16l-170 XR 2,774,128 12/1956 Secrist 28-73 2,900,291 8/1959 OConnell 161-150 XR 3,085,922 4/1963 Koller 161-67 3,228,790 1/1966 Sexsmith et al. 161170 XR FOREIGN PATENTS 574,562 4/1959 Canada.

ROBERT F, BURNETT, Primary Examiner.

ALEXANDER WYMAN, Examiner.

R. H. CRISS, Assistant Examiner. 

1. A METHOD FOR PRODUCING A TEXTILE ARTICLE WHICH COMPRISES: BLENDING 50-95% BY WEIGHT STRUCTURAL FIBERS WITH 550% BY WEIGHT BINDER FIBERS, BOTH STRUCTURAL AND BINDER FIBERS BEING CRIMPED STAPLE-LENGTH FIBERS COMPOSED OF LINEAR POLYESTERS, THE POLYESTER MAKING UP THE BINDER FIBERS BEING NORMALLY SOLID AND HAVING A MELTING POINT BELOW THAT OF THE POLYESTER MAKING UP THE STRUCTURAL FIBERS; CARDING THE BLEND OF FIBERS TO SUBSTANTIALLY PARALLELIZE THE FIBERS AND ENSURE UNIFORM DISPERSION OF THE BINDER FIBERS AND STRUCTURAL FIBERS; STACKING THE CARDED BLEND TO FORM A MULTI-PLY ASSEMBLY WITH THE FIBERS ALL GENERALLY ALIGNED IN THE SAME DIRECTION; HEATING THE ASSEMBLY AT A TEMPERATURE BETWEEN THE MELTING POINT OF THE BINDER FIBERS AND THE MELTING POINT OF THE STRUCTURAL FIBERS TO THEREBY CAUSE THE POLYESTER MAKING UP THE BINDER FIBERS TO RETRACT INTO DROPLET FORM AND BOND THE STRUCTURAL FIBERS TO ONE ANOTHER AT THEIR CROSS-OVER POIINTS THROUGHOUT THE ASSEMBLY; CUTTING THE ASSEMBLY AT AN ANGLE TRANSVERSE TO THE PARALLELIZED FIBERS TO PROVIDE A POROUS, FLEXIBLE, SELF-SUPPORTING SHEET HAVING FACES COMPOSED ESSENTIALLY OF FIBER ENDS; AND LAMINATING A FACE OF THE SHEET WITH A BACKING. 